Hellenic journal of nuclear medicine最新文献

Fibroblast activation protein inhibitor (FAPI) positron emission tomography/computed tomography (PET/CT) is a multimodal imaging technique that combines PET and CT, utilizing FAP inhibitors as radiotracers. Fibroblast activation protein, a serine protease highly expressed in many epithelial tumor-associated fibroblasts, plays a crucial role in tumor stroma formation and remodeling. Through the detection of FAP expression, FAPI PET/CT facilitates the diagnosis and staging of both benign and malignant pulmonary tumors. In contrast to traditional fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET/CT focusing on glucose metabolism, FAPI PET/CT offers benefits such as enhanced specificity, reduced background noise, accelerated imaging speed, and decreased radiation exposure. This review provides an overview of the progress in applying FAPI PET/CT and ¹⁸F-FDG PET/CT in pulmonary malignancies and discusses current challenges and future prospects.

Objective: Positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) are complementary in staging of nasopharyngeal carcinoma (NPC). The combination of MRI and functional imaging from PET in PET/MR is promising in NPC management. Diagnostic performance of PET/CT and PET/MR was compared in 46 patients with histologically confirmed NPC under different disease scenarios, including primary non-metastatic cases, primary metastatic cases, recurrence and/or metastasis after treatment, and post-treatment follow-up cases.

Subjects and methods: Forty-six patients underwent both PET/CT and PET/MR in the same day. Primary tumor extension into risk-stratified anatomic structures, retropharyngeal and cervical lymph node metastasis, distant metastasis and post-treatment follow-up results, were compared.

Results: For high-risk structures, PET/MR detected two more sides of tensor/levator veli palatine muscle involvement, one more case of clivus involvement, and ruled out 12 false-positive sides of prevertebral muscle involvement by PET/CT. For medium-risk structures, PET/MR detected four more sides of medial pterygoid muscle involvement. For low-risk structures, abnormal signal on massa lateralis atlantis was detected by PET/MR. PET/MR detected 14 more positive retropharyngeal lymph nodes and more liver micrometastases than PET/CT. Overall, PET/MR changed two patients' T staging.

Conclusion: Positron emission tomography/MR outperforms PET/CT in delineating muscle, skull-base bone, and nodal involvement, and identifying liver micrometastases, may serve as a single-step staging modality for NPC.

Objective: Cryptococcus, a genus of fungi, primarily includes Cryptococcus neoformans and Cryptococcus gattii, both known to cause human infections. Skeletal infections are rare, and there have been no reported cases of bone cryptococcal infection in conjunction with differentiated thyroid carcinoma.

Subject and methods: A 56-year-old female presented with a one-month history of "cough and throat irritation." Chest CT revealed scattered small nodules in both lungs,suggestive of metastasis.There was minimal inflammation in both lungs, and scattered lymph nodes were observed in the mediastinum and upper pulmonary hilum.

Results: The patient was diagnosed with differentiated thyroid carcinoma complicated by cryptococcal infection. Antifungal treatment with itraconazole 200mg/day was initiated, and after 3 months, clinical symptoms disappeared, with a reduction in lung nodules observed in follow-up chest CT.

Conclusion: When diagnosing distant metastasis in differentiated thyroid carcinoma, a comprehensive analysis combining imaging studies and serum thyroid globulin plays a complementary role, as illustrated in this case of differentiated thyroid carcinoma concurrent with cryptococcal infection.

Objective: To explore the potential of intratumoral metabolism and its heterogeneous parameters, as measured by preoperative fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) imaging, to predict mediastinal occult lymph node metastasis in cN0 lung invasive adenocarcinoma.

Subjects and methods: Seventy five patients were consecutively enrolled from January 2018 to December 2022. All patients underwent ¹⁸F-FDG PET/CT scans within two weeks before surgery, and had mediastinal lymph node metastasis confirmed by pathologic diagnosis after surgery. Metabolic parameters including the maximum standardized uptake value (SUVmax), mean SUV (SUVmean), maximum average SUV (SUVpeak), tumor metabolic volume (MTV), and metabolic heterogeneity (HF) were measured. The relationship between primary focal metabolism, its heterogeneity parameters, and occult mediastinal lymph node metastasis was analyzed using an independent-sample t-test, analysis of covariance, and Mann-Whitney U test. A multivariate logistic regression model was used to analyze independent risk factors for mediastinal lymph node metastasis, while the receiver operating characteristic (ROC) curve assessed the predictive value of metabolic heterogeneity parameters for mediastinal occult lymph node metastasis.

Results: A total of 20 out of 75 patients (26.7%) were pathologically confirmed to have mediastinal lymph node metastasis. Analysis of covariance showed that the SUVmax, SUVmean, SUVpeak and MTV were significantly higher in patients with metastasis than in those without (all P<0.05). The metabolic heterogeneity parameters HF2 and HF3 were significantly higher in patients with mediastinal lymph node metastasis than in those without (P=0.013, 0.001), but not HF1. Multivariate Logistic regression analysis identified that tumor size, SUVmax, SUVpeak, lymph node SUVmax, and HF2 of the primary tumor as independent risk factors for mediastinal lymph node metastasis. Metabolic heterogeneity 3 demonstrated high predictive value for mediastinal occult lymph node metastasis (AUC=0.720, P=0.004).

Conclusion: Metabolism and heterogeneity, as measured by preoperative ¹⁸F-FDG PET/CT in lung invasive adenocarcinoma, potentially have clinical value for predicting mediastinal occult lymph node metastasis.

Objective: This paper reviews the current status and future development of positron emission tomography/magnetic resonance (PET/MR) co-imaging technology in the field of cardiovascular diseases.

Material and methods: By combining PET and MRI, PET/MR co-imaging provides comprehensive assessment advantages by simultaneously offering functional and anatomical information.

Results: Firstly, the basic principles of PET/MR are introduced, and the current state is discussed. Subsequently, a detailed discussion on the application of PET/MR in the diagnosis of cardiovascular diseases, including early detection and comprehensive assessment of conditions like coronary artery disease and myocarditis, is presented. Finally, the challenges and future prospects in PET/MR applications are outlined.

Conclusion: Despite facing several technical challenges, PET/MR co-imaging technology is expected to play a crucial role in the early diagnosis, treatment, and research of cardiovascular diseases, paving the way for new directions and possibilities in future medical imaging research.

Objective: Numerous studies have shown that gallium-68-labeled fibroblast activation protein inhibitor (⁶⁸Ga-FAPI) positron emission tomography/computed tomography (PET/CT) scans would yield high intra-tumoral tracer uptake and low uptake in normal tissues as background, thus allowing for excellent visualization of lesions in the cancer microenvironment. This study set out to compare the suitability of novel ⁶⁸Ga-FAPI-46 PET versus routine fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET and other few cases of ⁶⁸Ga-DOTATATE/⁶⁸Ga-Pentixafor PET/CT for the assessment of different types of cancer.

Subjects and methods: A retrospective analysis of 11 patients (6 males, 5 females; average age: 53 years, range: 10-58 years) with histopathologically confirmed, well-differentiated adenocarcinoma, medullar thyroid cancer (MTC), papillary thyroid carcinoma (PTC), cervical, gastric, glioblastoma multiform (GBM), colon, Ewing's sarcoma, and breast cancer was performed. These patients underwent PET/CT scans using four different radiotracers (9 ¹⁸F-FDG, 11 ⁶⁸Ga- FAPI, 3 ⁶⁸Ga-DOTATATE, and 1 ⁶⁸Ga-Pentixafor). The patients' PET/CT images were visually evaluated for cancer detection, and analyzed semi-quantitatively through image- derived metrics, such as target-to-background ratio (TBR) and maximum standardized uptake value (SUVmax), for recurrence and metastasis.

Results: The study of 11 patients revealed that ⁶⁸Ga-FAPI-46 was more effective than other tracers for detecting metastases, with 55 vs. 49 metastases in the lymph nodes, 4 vs. 3 in the liver, and 4 vs. 3 in the bones detected in comparison to ¹⁸F-FDG. No significant differences were observed in ⁶⁸Ga-DOTATATE and ⁶⁸Ga-Pentixafor PET images. In addition, in five patients, the SUVmax and TBR values in ⁶⁸Ga-FAPI-46 PET images were significantly higher than those in ¹⁸F-FDG PET images for lymph nodes and bone metastases. Although the SUVmax in ⁶⁸Ga-FAPI-46 and ¹⁸F-FDG PET images for liver metastases was comparable, ⁶⁸Ga-FAPI- 46 had a significantly higher TBR than ¹⁸F-FDG.

Conclusion: Our findings suggest that FAPI PET/CT is not suitable for evaluating GBM and Ewing sarcoma but generally outperforms ¹⁸F-FDG PET/CT in various types of breast cancer, gastrointestinal, gynecological, PTC and MTC. However, larger trials are needed to validate these preliminary findings.

Tuberculosis continues to be a significant global health concern, impacting various parts of the body aside from the lungs. Muscular tuberculosis (MT), while rare, poses diagnostic hurdles due to its nonspecific imaging features. Presenting a case of a 66-year-old man with multiple MT lesions, we underscore the vital contribution of positron emission tomography/computed tomography (PET/CT) in both diagnosis and treatment assessment. Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET/CT imaging revealed hypermetabolism in bilateral chest and back muscles, facilitating accurate diagnosis and monitoring treatment response. This highlights the pivotal role of ¹⁸F-FDG PET/CT in managing MT, especially in cases with multiple lesions.

Objective: This study was carried out to understand whether Q.Clear and ordered subset expectation maximization (OSEM), reconstruction algorithms used in fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) applications, and parameters such as time of flight (TOF) and point spread function (PSF) cause different results in semi-quantitative measurements.

Subjects and methods: Raw PET data of 264 patients who were referred to ¹⁸F-FDG PET/CT imaging with the purpose of evaluation of known or suspicious malignant disease were reconstructed separately with Q.Clear (GE Healthcare), a BPL, an OSEM algorithm, PSF (SharpIR®) and TOF (VUE Point FX®) methods. Each patient's liver, mediastinal blood pool, metabolic tumor volume (MTV), total lesion glycolysis (TLG), and standardized uptake values (SUV) (SUVmax, SUVmean, and SUVpeak) of a total of 264 lesions selected from the patients were performed.

Results: β350+ToF yielded higher measurement results than all other variables for all of the lesion SUVmax, lesion SUVmean, L/AP SUVmax, and L/AP SUVmean parameters. OSEM+ToF and OSEM+TOF+PSF algorithms yielded higher mean and median SUVmax values for the reference structures (liver and mediastinum) and for lesions SUVmax and SUVmean values were statistically significantly lower than the β350+ToF method. The method with the lowest mean value for the L/Liver SUVmax variable was OSEM+ToF 4iter16ss (mean=1.76), while the method with the highest mean value was β350+ToF (mean=2.26). β350+ToF was the reconstruction method with the highest ratios for L/AP SUVmax and SUVmean for both lesions below and above 1 cm. β350+ToF algorithm had also statistically significantly higher results for these variables compared to all other parameters in malignant lesions.

Conclusion: When comparing ¹⁸F-FDG PET/CT images, the use of different reconstruction algorithms may lead to misleading results, especially in the evaluation of response to treatment of malignancies.